NOTES ON THE SALMO SALAR SPECIMEN — MORROW. 187 



has a wide articulating surface on its inner side or heel for its 

 union with the radius upon which it moves, this surface is fur- 

 nished with the usual lining and ligaments of such joints ; from its 

 inner to outer heel transversely it is in breadth f of an inch. 



Outer side of the pectoral Jin. — The heel of the first or upper 

 ray is § of an inch in length, and nearly at right angles to its shaft, 

 the heel inclining away from its supporting bone, and at the 

 same time turned towards the ventral aspect of the fish. 

 The heels of the remaining rays gradually increase their angles 

 or have less abrupt curves until the last two or three rays, 

 when their curves again become sharper, the lengths of all de- 

 creasing, but the outer heel of the lowest or short ray preserves 

 nearly the normal shape, and projects an \ of an inch below the 

 supporting ossicle. On its inner side the heel of the lower ray is 

 very stout, and its edge inclining downwards gives it a broad 

 termination for the accommodation of the articular joint. The 

 heels of the next six raj^s gradually decrease in their length and 

 curves until the 8th ray is nearly straight ; 9th, 10th, 11th, 

 12th and 13th rays are also nearly straight, but closely crowded 

 together, and the inner heel of the 14th is curved upwards and al- 

 most overlaps the end of No. 13 ; the outer heel of 14 is, from out- 

 side to outside, \ of an inch below the inner extremity. All the 

 rays are on each side attached to the base of the fin, 

 by strong cartilage , which fills the division of or the space 

 between the rays, so much so that without destroying the fin, 

 which at present cannot be spared, it is impossible for me to give 

 a more particular description of it. 



At the junction of the clavicles, which are connected by carti- 

 lage and closely attached to their united ends by strong fatty 

 tissue, is the urohyal bone, in this specimen it is If inches in 

 length, and f of an inch in height at its posterior extremity ; at 

 this point begins its ventral transverse plate, for half an inch of 

 its length it is very narrow, but it rapidly widens until it 

 attains f of an inch, taking a lanciolate form. This bone is per- 

 pendicular to the body of the fish, and by its anterior end it is 

 attached to the hyoid bones. 



This brings us now to the head of the fish on the ventral 



